Para-aramid polymers are notoriously difficult to dissolve and that difficulty has led to somewhat delayed development of uses for extremely useful polymeric materials. To the present time, for example, poly(para-phenylene terephthalamide) has been spun in a solution of sulfuric acid because a solvent system having the solvent strength of sulfuric acid has been required to make the solution. There now has been discovered a solvent system with adequate solvent strength to yield relatively concentrated solutions of polymers, such as poly(para-phenylene terephthalamide) (PPD-T).
It is well known in the literature that sodium hydride reacts with dimethylsulfoxide under anhydrous condition with evolution of hydrogen to provide the so-called "dimsyl" anion. Addition of proton donors such as water and alcohols reverse the process with regeneration of the original dimethylsulfoxide. The dimsyl anion can be used to remove protons from a variety of compounds such as amines, amides, acetylenes and weakly acid hydrocarbons. Typical reactions have been described by Corey and Chaykovsky (J. Am. Chem. Soc., 87, 1345-1353, 1965), among others. Takayanagi and Katayosi have extended the reaction of the dimsyl anion with amides to relatively low molecular weight polyamides and have used the amide anion thus formed to produce a variety of N-substituted products. J. Poly. Sci. (Polymer Chemistry Edition) 19, 1133 (1981).